Hi @sheldonhull,
This answer wasn’t relevant at the time of the original question, but at this point I think the best answer is to wait for Terraform 0.13.0 to be released and then to use its support for installing community providers from Terraform Registry. The 0.13.0 release is currently in beta, and the ability to publish community providers to the public registry is also currently in (a separate) beta, so final releases of both should follow soon.
The old answer was to include the provider binaries in the configuration bundle uploaded to Terraform Cloud, under the terraform.d/plugins/linux_amd64 directory relative to whatever directory Terraform Cloud will be running Terraform in. That answer will grow obsolete soon, so unless you have an urgent need to get this done today I would suggest holding and instead perhaps suggesting to the maintainers of the providers you are interested in that they participate in the Terraform Registry community providers beta, which will make the provider available for automatic installation from Terraform 0.13.0 onwards.